Bight 08 Invertebrate Biomass

Regional monitoring has become an important component of assessing the status of our coastal resources in the Southern California Bight (SCB). The 2008 Regional Marine Monitoring Program (Bight‟08) is the fourth in a series of regional marine monitoring efforts beginning in 1994 and repeated again in 1998 and 2003. More than 90 different organizations encompassing regulatory, regulated, academic, and non-governmental agencies collaborated to create Bight '08. Collectively, these organizations asked two primary questions: 1) What is the extent and magnitude of impact in the SCB? 2) Does the extent and magnitude of impact vary among different habitats of interest? Bight '08 had six components; coastal ecology, shoreline microbiology, water quality, wetland eutrophication, rocky subtidal, and areas of special biological significance. The Coastal Ecology component measured sediment chemistry, sediment toxicity, benthic infauna, fish assemblages and bioaccumulation. The focus of this report is on sediment chemistry. A stratified random design was selected to ensure an unbiased sampling approach to provide areal assessments of environmental condition. There were 12 strata selected including three mainland shelf (5-30m, 30-120m, 120-200m), upper mainland slope (200-500m), lower slope and basin (500-1000m), marinas, ports, bays, estuaries, and the Channel Islands National Marine Sanctuary (30-200m surrounding Santa Barbara, Anacapa, Santa Rosa, Santa Cruz, and San Nicolas Islands). Demersal fishes and benthic macroinvertebrates that live on soft-bottom habitat are an important part of the marine ecosystem. Soft-bottom habitat comprises the majority of the Southern California Bight (SCB) area and fish species number in the hundreds. Demersal fish and megabenthic invertebrates are regularly monitored in ocean outfall monitoring programs using otter trawls because these organisms have responded to wastewater inputs historically. However, previous monitoring has also demonstrated that demersal fish and megabenthic invertebrates respond to natural variations in the ocean including depth, latitude and water temperature cycles (i.e., El Niño Southern Oscillation, Pacific Decadal Oscillation). This naturally occurring variation affects large spatial scales and complicates interpretation of localized ocean outfall monitoring. The objective of the trawl component of 2008 Southern California Bight Regional Marine Monitoring Program (Bight'08) was to: 1) estimate the extent and magnitude of community changes at regional scales; and 2) determine the trends in these regional-scale changes. Environmental managers want to know how their site(s) compare to the natural variation of outlying areas within the SCB. Estimating the amount of area (i.e., number of acres, percentage of the total) that differs from these reference conditions directly address large-scale management concerns. Bight'08 is the fourth in a series of regional trawl monitoring surveys dating back to 1994. Comparisons in spatial extent of fish and megabenthic invertebrate communities among surveys form the basis of the trends evaluation. Trawl samples were collected from 143 stations from Point Conception to the U.S.-Mexico Border at depths of 3-485 m from July to October 2008 using a stratified-random probability-based survey design. Stratification focused on known ecological zones including bays and harbors, three depths on the mainland continental shelf (5-30, 30-120, and 120-200m), and the upper continental slope (200-500m). For each trawl, organisms were identified to species, counted, weighed, fish length measured, checked for external anomalies or diseases, and then returned to the sea. Quality assurance is an important component of the Bight'08 program. Overall, data quality was high and no data were censored due to quality related issues. However, several concerns were identified including presurvey evaluations and in-study field audits, ensuring representative on-bottom net times, and accuracy of voucher specimen identifications. While these deviations did not impact the conclusions of the study, future surveys should address these concerns. Demersal fish and invertebrate communities of the SCB were relatively healthy in 2008 based on biointegrity assessment tools. Approximately 96% of the SCB had fish communities that were similar to reference conditions. In addition, approximately 84% of the SCB had megabenthic invertebrate communities that were similar to reference conditions. Nonreference conditions were found primarily on the inner continental shelf (200m) was distinctly different from the continental shelf (120-200m). These naturally occurring differences are an important reminder for those trying to assess the impacts from anthropogenic discharges as one crosses ecological gradients. Most changes in regional fish species composition of the SCB since the early 1970s are likely related to cold and warm regimes of the Pacific Decadal Oscillation and the occurrence of two El Niños. Physical oceanographic conditions are known to influence biological condition in the SCB. Comparing the bathymetric distribution of species in fish foraging guilds illustrated the most similarity during cold regimes (1972, 2003, 2008), less similarity in 1994 (warm), and least similarity during the 1998 El Niño (very warm). These naturally occurring differences are an important reminder for those trying to assess the impacts from anthropogenic discharges as one crosses ecological gradients. Debris was found throughout most (90%) of the SCB, but generally in trace amounts. Natural debris was observed three times as frequently as anthropogenic debris. Marine (seaweeds) and terrestrial (woody) debris were the most common natural debris. Plastics were the most common anthropogenic debris. Anthropogenic debris was found most frequently, and in greatest quantities, in the central SCB presumably due to its proximity to the urban center of Los Angeles and Orange Counties. The frequency and quantity of debris co-varied with rainfall quantity in the winter preceding each sampling campaign of the last four regional surveys. A number of recommendations were identified for planning and implementing the next Bight regional survey. These recommendations included: 1) partnering with the Ocean Protection Council's Marine Monitoring Enterprise, the agency tasked with monitoring the effectiveness of pending Marine Protected Areas; 2) improved training of field teams to ensure continued QA; and 3) upgrading the tools used by trawl scientists for assessing impacts. Reports and documentation for Bight 08 can be found on the SCCWRP website at www.sccwrp.org